A conventional 75 ohm and 300 ohm coupler shown in FIGS. 1 and 2, comprises a housing tube A made of aluminum having two ends AO, AO, an end fitting with a large-diameter neck BO in a connecting head B, a central hollow A1 for depositing a PC board C therein securely, the other end of housing tube A holding a small soft wire holder A2 in the central hollow A1. The wire holder A2 is provided with a wire groove A20 to pinch therein two 300 ohm lead wires C1, C1, and an insulating plastic tube A3 is fitted around the housing tube A for insulating it.
Another conventional coupler shown in FIGS. 3 and 4, comprises a housing tube A' made of plastic, a wire grooves A1' prolead in one end of the housing tube A' for pinching two 300 ohm lead wires C1', C1', a connecting head B' having a positive terminal B1' and a negative terminal B1' of 75 ohm lead wires of a television antenna connected with a PC board C', which is then connected with the 300 ohm lead wires C1', C1'.
These conventional couplers are rather complicated and thus are expensive.